[Spice-devel] [PATCH v4 0/2] protocol: add gl scanout support

[Marc-André Lureau]

Hi

----- Original Message -----
> On Thu, Jan 14, 2016 at 10:33:04AM -0500, Marc-André Lureau wrote:
> > This is just arbitrary numbers. What I know is this works well for the
> > last year, and I don't expect it to need changes soon.
> 
> This is not really what I'm asking...
> Let's say we add all of this to spice-protocol, we release clients,
> servers, ... depending on this.
> 
> Then we realize in order to achieve X or Y, we need to do things
> slightly differently. What is our escape plan there? Do we have an easy
> way out without breaking older clients? If yes, all fine with me, if
> not, we are back to my initial question, do we want to/how do we mark
> these additions as unstable while things settle down for a bit?

At the very worst case (really don't like talking that way, that's so much in the air), we can always keep those messages around, and bring a new GL_SCANOUNT2 with new messages for compatible client & servers, no? I really don't see the difference with other additions or changes to the protocol.

> 
> I'm not asking that we do some very complicated work now and wait
> undefinitely, I'm precisely trying to ask if we'll be able to
> evolve this as usual.

I don't see why not.  Nobody can say this will work forever or for how long. Say dmabuf disappear (like flink before), then we will add new messages/flags to deal with it. The proposed protocol will still remain valid for host with dmabuf.